U.S. patent application number 15/661557 was filed with the patent office on 2018-05-10 for antenna device including parabolic-hyperbolic reflector.
The applicant listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Gennadiy Aleksandrovich EVTYUSHKIN, Alexander Nikolaevich KHRIPKOV, Anton Sergeevich LUKYANOV, Artem Yurievich NIKISHOV, Elena Aleksandrovna SHEPELEVA.
Application Number | 20180131101 15/661557 |
Document ID | / |
Family ID | 62064495 |
Filed Date | 2018-05-10 |
United States Patent
Application |
20180131101 |
Kind Code |
A1 |
EVTYUSHKIN; Gennadiy Aleksandrovich
; et al. |
May 10, 2018 |
ANTENNA DEVICE INCLUDING PARABOLIC-HYPERBOLIC REFLECTOR
Abstract
An antenna device is provided. The antenna device includes a
reflector having a profile of a parabolic shape in a first
cross-section cut parallel to a first direction and a profile of a
hyperbolic shape in a second cross-section, the second
cross-section being cut perpendicular to the first direction and
crossing the first cross-section at a right angle and a radiating
structure having at least one phased antenna array adapted to
illuminate at least part of the reflector and to scan a beam. The
edges of the profile of the parabolic shape of the first
cross-section are formed to be directed toward the radiating
structure. The edges of the profile of the hyperbolic shape of the
reflector are formed to be directed away from the radiating
structure. The antenna device may be diversified depending on
various embodiments.
Inventors: |
EVTYUSHKIN; Gennadiy
Aleksandrovich; (Moscow, RU) ; NIKISHOV; Artem
Yurievich; (Moscow, RU) ; LUKYANOV; Anton
Sergeevich; (Moscow, RU) ; SHEPELEVA; Elena
Aleksandrovna; (Kostroma, RU) ; KHRIPKOV; Alexander
Nikolaevich; (Moscow, RU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Suwon-si |
|
KR |
|
|
Family ID: |
62064495 |
Appl. No.: |
15/661557 |
Filed: |
July 27, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01Q 15/16 20130101;
H01Q 3/30 20130101; H01Q 19/175 20130101; H01Q 1/246 20130101 |
International
Class: |
H01Q 15/16 20060101
H01Q015/16; H01Q 1/24 20060101 H01Q001/24 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 9, 2016 |
RU |
2016143930 |
Jun 1, 2017 |
KR |
10-2017-0068514 |
Claims
1. An antenna device comprising: a reflector having a profile of a
parabolic shape in a first cross-section cut parallel to a first
direction and a profile of a hyperbolic shape in a second
cross-section, the second cross-section being cut perpendicular to
the first direction and crossing the first cross-section at a right
angle; and a radiating structure having at least one phased antenna
array adapted to illuminate at least part of the reflector and to
scan a beam, wherein edges of the profile of the parabolic shape of
the first cross-section are formed to be directed toward the
radiating structure, and wherein edges of the profile of the
hyperbolic shape of the reflector are formed to be directed away
from the radiating structure.
2. The antenna device of claim 1, wherein the phased antenna array
comprises linearly-arranged phased antennas, and wherein the phased
antennas are placed on a same plane as one of the second
cross-sections, and wherein the phased antennas are configured to
be orthogonal to a symmetry axis of the profile of the hyperbolic
shape.
3. The antenna device of claim 1, wherein the radiating structure
comprises at least two phased antenna arrays, and wherein each of
the at least two phased antenna arrays are configured to illuminate
a different part of the reflector.
4. The antenna device of claim 1, wherein the phased antenna array
is configured to perform dual-polarized beamforming.
5. The antenna device of claim 1, wherein the phased antenna array
comprises phased antennas, and wherein the phased antenna comprises
a waveguide antenna.
6. The antenna device of claim 5, wherein the waveguide antenna
comprises a waveguide with a side directed toward the reflector
open and the opposite side closed, and wherein the waveguide is
formed inside one of a metal hollow or a metalized hollow.
7. The antenna device of claim 5, wherein the waveguide antenna
comprises a waveguide formed in a metal or metalized hollow; and a
microstrip line for providing feed into the waveguide.
8. The antenna device of claim 7, wherein the waveguide antenna
comprises: a first waveguide member having a first part of the
waveguide, a second waveguide member having a second part of the
waveguide, and at least one printed circuit board having the
microstrip line, and wherein the printed circuit board is arranged
on a plane perpendicular to an axis of the waveguide between the
first part and the second part to be clamped between the first
waveguide member and the second waveguide member.
9. The antenna device of claim 8, wherein the waveguide antenna
further comprises: furrows formed in the first waveguide member and
the second waveguide member, respectively, and wherein the furrows
are configured to correspond to an area in which the microstrip
line is formed.
10. The antenna device of claim 8, wherein the microstrip line
linearly extends on the printed circuit board, and wherein one end
of the microstrip line is configured to: extend into the waveguide,
and form a right angle with an inner wall of the waveguide, to form
an excitation waveguide probe in the waveguide.
11. The antenna device of claim 8, wherein microstrip lines are
symmetrically arranged on either side of the printed circuit
board.
12. The antenna device of claim 8, wherein the waveguide antenna
comprises two of the printed circuit boards, and wherein the
microstrip line placed on one of the printed circuit boards is
arranged to be perpendicular to the other micro strip line placed
on the other printed circuit board.
13. The antenna device of claim 9, wherein the furrows are placed
in the first waveguide member and the second waveguide members
based upon an impedance requirement for the waveguide antenna.
14. The antenna device of claim 12, wherein the waveguide antenna
further comprises a dummy waveguide member arranged between two of
the printed circuit boards.
15. The antenna device of claim 14, wherein the dummy waveguide
comprises an opening corresponding to the first part or the second
part.
16. The antenna device of claim 7, wherein the waveguide antenna
further comprises protrusions formed along an inner wall of the
waveguide, and the protrusions are configured to lower a critical
frequency of the waveguide antenna.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit under 35 U.S.C. .sctn.
119(a) of a Russian patent application filed on Nov. 9, 2016 in the
Russian Patent Office and assigned Serial number 2016143930 and of
a Korean patent application filed on Jun. 1, 2017 in the Korean
Intellectual Property Office and assigned Serial number
10-2017-0068514, the entire disclosure of each of which is hereby
incorporated by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to antenna devices. More
particularly, the present disclosure relates to an antenna device
including a reflector.
BACKGROUND
[0003] Constantly increasing demands of users motivates rapid
development of mobile communication technologies. Currently, fifth
generation (5G) millimeter-wave networks are being actively
developed. The 5G millimeter-wave networks may require higher
performance based on user experience and including such factors as
ease of connectivity with nearby devices and improved energy
efficiency. Millimeter-wave technologies encounter a variety of
fundamental challenges, which are associated with physics of
antenna arrays, structure of a high-speed transceiver, and the
like.
[0004] Still remaining main tasks for integration of
millimeter-wave antennas are to reduce cost, decrease interference
level, and provide required communication quality and energy
efficiency. Further, a communication channel shall maintain
stability when a communicating mobile device changes its position.
Accordingly, the following requirements may be imposed on e.g.,
antennas of base stations:
[0005] 1) high gain,
[0006] 2) wide scan angles,
[0007] 3) high directivity,
[0008] 4) low sidelobe level,
[0009] 5) dual-polarized beamforming to increase rate and improve
stability of data transmission, and
[0010] 6) high efficiency of the antenna.
[0011] FIG. 1 shows configuration of antennas in a base station
according to the related art.
[0012] Referring to FIG. 1, a very important task in operation of
scanning antennas is to increase the scan angle, which in turn may
enhance the efficiency of the system. The scan angle of a
traditional antenna array is generally restricted by .+-.45 degrees
in order not to cause a significant reduction in gain and an
excessive increase in the sidelobe level. Therefore, as shown in
FIG. 1, in configuring a traditional base station (or BS), four
antennas BSA1, BSA2, BSA3, and BSA4 each having a scan angle of
.+-.45 degrees, may be arranged to cover an area of 360 degrees
around the base station. The use of three antennas instead of four,
to cover the entire coverage area (i.e., to provide a desired level
of waves for the entire coverage area), could significantly
alleviate requirements for the complexity of control and
distribution devices on the side of the base station transceiver,
decrease the base station dimensions, and simplify and speed up
installation of the base station. Therefore, to configure a base
station with three antennas, it would be desirable that each of the
three antennas has a scan angle of more than .+-.60 degrees not
less than .+-.60 degrees.
[0013] To expand the scan angle in the millimeter-wave
communication frequency range, special means may be required. For
example, a conformal antenna array (cylindrical type), Luneburg
lens antennas, and switched axisymmetric antennas are currently
used for increasing the scan angle. These types of antennas may
provide a scan angle of .+-.90 and more. However, they have some
disadvantages: namely, they include a sophisticated switching unit
that introduces additional loss, require large spatial dimensions,
and have low efficiency of the antenna aperture.
[0014] Traditional antenna arrays may obtain an extended scanning
beam by means of special structures installed in front of the
array. These structures may cause additional deviation of the wave
front, and are generally used for large broad-side arrays.
[0015] There are some millimeter-wave solutions that approach the
aforementioned requirements to some extent according to the related
art.
[0016] FIGS. 2, 3, 4, and 5 show examples of millimeter-wave
antennas according to the related art.
[0017] Referring to FIG. 2, the publication "An E-band Cylindrical
Reflector Antenna for Wireless Communication Systems" 7th European
Conference on Antennas and Propagation (EUCAP2013)" discloses a
cylindrical reflector antenna designed for high frequency
applications and having a high gain and relatively low losses.
However, this antenna is incapable of scanning, has an efficiency
of about 60% and operates with a single polarization only.
[0018] Referring to FIG. 3, another antenna of the related art for
application at 23 GHz frequencies is disclosed in the publication
"Cylindrical-parabolic reflector with printed antenna structures"
IHTM-CMTM, University of Belgrade Journal of Microelectronics,
Electronic Components and Materials, Vol. 43, No. 2(2013), 97-102.
The disclosed antenna has a radiating structure in the form of a
microstrip antenna array of dipoles, and a cylindrical reflector.
Like the previous example, this antenna has no scanning ability and
operates with a single polarization only. Furthermore, a microstrip
feeder of the antenna disclosed by the university of Belgrade
journal operates with an efficiency of only 56% because the losses
in feeding radiators reach 2-3 dB. In the millimeter-wave
communication, the losses in the microstrip feeder may further
increase due to dielectric material loss and manufacturing defects
(any irregularities, thickening, narrowing, notches, curvatures,
corners, etc. may cause re-reflection, parasitic radiation, etc.).
Therefore, the distributed system of the feeder path may be a
disadvantage for millimeter antennas.
[0019] Referring to FIG. 4, another antenna of the related art is
disclosed in the publication "The Design on the Antenna Array with
High Gain and Scanning Beam" Lu Zhiyong, the 54th Research
Institute of CETC, Shijiazhuang, 050081, China, International
Conference on Microwave and Millimeter Wave Technology (ICMMT),
2012. A cylindrical (parabolic) reflector is illuminated by a
special array to form a scanning beam. This antenna, like the
previous antennas, operates with a single polarization and has a
relatively low efficiency (about 60%). Furthermore, the antenna has
a very limited scan angle (.+-.20 degrees), so nine antennas are
required to cover an area of 360 degrees, and given its extreme
complexity, the use of such an antenna in base stations for mobile
communications is hardly suitable.
[0020] Referring to FIG. 5, as another millimeter-wave antenna,
Thomson CSF Radar Maser-T antenna has been proposed. The antenna is
a complex scanning antenna array consisting of a plurality of
linear microstrip antenna arrays, and the scanning antennas are
connected to the respective transceiver circuits. However, despite
all the complexity, this antenna is restricted by a scan angle of
.+-.40 degrees, and its microstrip structure may cause high loss in
the feeder lines and low antenna efficiency.
[0021] Such technologies of the related art are not suitable for
providing antenna devices, which could simultaneously meet all of
the above requirements.
[0022] The above information is presented as background information
only to assist with an understanding of the present disclosure. No
determination has been made, and no assertion is made, as to
whether any of the above might be applicable as prior art with
regard to the present disclosure.
SUMMARY
[0023] Aspects of the present disclosure are to address at least
the above-mentioned problems and/or disadvantages and to provide at
least the advantages described below. Accordingly, an aspect of the
present disclosure is to provide an antenna device capable of
dual-polarized beamforming and having increased scan angle.
[0024] In accordance with an aspect of the present disclosure, an
antenna device is provided. The antenna device includes a reflector
having a profile of a parabolic shape in a first cross-section cut
parallel to a first direction and a profile of a hyperbolic shape
in a second cross-section, the second cross-section being cut
perpendicular to the first direction and crossing the first
cross-section at a right angle, and a radiating structure having at
least one phased antenna array adapted to illuminate at least part
of the reflector and to scan a beam. The edges of the profile of
the parabolic shape of the first cross-section are formed to be
directed toward the radiating structure. The edges of the profile
of the hyperbolic shape of the reflector are formed to be directed
away from the radiating structure.
[0025] Other aspects, advantages, and salient features of the
disclosure will become apparent to those skilled in the art from
the following detailed description, which, taken in conjunction
with the annexed drawings, discloses various embodiments of the
present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The above and other objects, features, and advantages of
certain embodiments of the present disclosure will be more apparent
from the following description taken in conjunction with the
accompanying drawings, in which:
[0027] FIG. 1 shows configuration of antennas in a base station
according to the related art;
[0028] FIGS. 2, 3, 4, and 5 show examples of millimeter-wave
antennas according to the related art;
[0029] FIG. 6 is a perspective view of an antenna device, according
to various embodiments of the present disclosure;
[0030] FIG. 7 is a cross-sectional view of an antenna device cut
along a line A-A' in FIG. 6 according to an embodiment of the
present disclosure;
[0031] FIG. 8 is a cross-sectional view of an antenna device cut
along a line B-B' in FIG. 6 according to an embodiment of the
present disclosure;
[0032] FIG. 9 is a graph representing measurements of radiation
properties of an antenna device including a cylindrical or
parabolic reflector of the related art according to an embodiment
of the present disclosure;
[0033] FIG. 10 is a graph representing measurements of radiation
properties of an antenna device including a parabolic-hyperbolic
reflector according to various embodiments of the present
disclosure;
[0034] FIG. 11 shows a configuration of a base station with an
antenna device according to various embodiments of the present
disclosure;
[0035] FIG. 12 is a perspective view of a phased antenna array of
an antenna device, according to various embodiments of the present
disclosure;
[0036] FIG. 13 is an exploded perspective view of an implementation
of a phased antenna of an antenna device, according to various
embodiments of the present disclosure;
[0037] FIG. 14 shows an implementation of a phased antenna of an
antenna device, according to various embodiments of the present
disclosure;
[0038] FIG. 15 is a cross-sectional view of a phased antenna cut
along a line C-C' in FIG. 14 according to an embodiment of the
present disclosure;
[0039] FIGS. 16 and 17 show feeding structures of an antenna
device, according to various embodiments of the present
disclosure;
[0040] FIG. 18 shows a vertical (elevation) plane radiation pattern
of an antenna device including a cylindrical or parabolic reflector
of the related art according to an embodiment of the present
disclosure;
[0041] FIG. 19 shows a vertical plane radiation pattern of an
antenna device, according to various embodiments of the present
disclosure; and
[0042] FIG. 20 shows calculation of a profile of a hyperbolic shape
of a reflector in an antenna device according to various
embodiments of the present disclosure.
[0043] Throughout the drawings, it should be noted that like
reference numbers are used to depict the same or similar elements,
features, and structures.
DETAILED DESCRIPTION
[0044] The following description with reference to the accompanying
drawings is provided to assist in a comprehensive understanding of
various embodiments of the present disclosure as defined by the
claims and their equivalents. It includes various specific details
to assist in that understanding but these are to be regarded as
merely exemplary. Accordingly, those of ordinary skill in the art
will recognize that various changes and modifications of the
various embodiments described herein can be made without departing
from the scope and spirit of the present disclosure. In addition,
descriptions of well-known functions and constructions may be
omitted for clarity and conciseness.
[0045] The terms and words used in the following description and
claims are not limited to the bibliographical meanings, but, are
merely used by the inventor to enable a clear and consistent
understanding of the present disclosure. Accordingly, it should be
apparent to those skilled in the art that the following description
of various embodiments of the present disclosure is provided for
illustration purpose only and not for the purpose of limiting the
present disclosure as defined by the appended claims and their
equivalents.
[0046] It is to be understood that the singular forms "a," "an,"
and "the" include plural referents unless the context clearly
dictates otherwise. Thus, for example, reference to "a component
surface" includes reference to one or more of such surfaces.
[0047] It will be understood that, although the terms first,
second, third, etc., may be used herein to describe various
elements, components, regions, layers and/or sections, these
elements, components, regions, layers and/or sections should not be
limited by these terms. These terms are only used to distinguish
one element, component, region, layer or section from another
region, layer or section. Thus, a first element, component, region,
layer or section discussed below could be termed a second element,
component, region, layer or section without departing from the
teachings of the present disclosure. Descriptions shall be
understood as to include any and all combinations of one or more of
the associated listed items when the items are described by using
the conjunctive term ".about. and/or .about.," or the like.
[0048] Furthermore, relative terms like `front`, `back`, `top`,
`bottom`, etc., set forth with respect to what are shown in the
drawings may be replaced with ordinal terms like `first .about.`,
`second .about.`, etc. The ordinal terms may be defined arbitrarily
or in the order of being mentioned, and may be arbitrarily changed
as necessary.
[0049] It will be further understood that the terms "comprises"
and/or "comprising," when used in this specification, specify the
presence of stated features, integers, operations, elements, and/or
components, but do not preclude the presence or addition of one or
more other features, integers, operations, elements, components,
and/or groups thereof.
[0050] Unless otherwise defined, all terms including technical and
scientific terms used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
present disclosure belongs. It will be further understood that
terms, such as those defined in commonly used dictionaries, should
be interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
[0051] FIG. 6 is a perspective view of an antenna device, according
to various embodiments of the present disclosure.
[0052] FIG. 7 is a cross-sectional view of an antenna device cut
along a line A-A' in FIG. 6 according to an embodiment of the
present disclosure.
[0053] FIG. 8 is a cross-sectional view of an antenna device cut
along a line B-B' in FIG. 6 according to an embodiment of the
present disclosure.
[0054] Referring to FIGS. 6 to 8, an antenna device 100 in
accordance with various embodiments of the present disclosure may
include a reflector 101 and a radiating structure (e.g., phased
antenna array 102). The radiating structure may include at least
one phased antenna array 102, which may be arranged to illuminate
at least part of the reflector 101. For example, the phased antenna
array 102 may emit (radio) waves toward the reflector 101, or
receive at least part of waves that enters from outside and are
reflected from the reflector 101.
[0055] According to various embodiments, if the radiating structure
includes one of the single phased antenna array 102, the phased
antenna array 102 may illuminate substantially the entire area of
the reflector 101. In an embodiment, if the radiating structure
includes a plurality of (e.g., at least two) phased antenna arrays
102, each of the phased antenna array 102 may illuminate a
different part of the reflector 101. For example, referring to
FIGS. 6 and 7, one of the two phased antenna arrays 102 may
illuminate the upper half of the reflector 101 while the other may
illuminate the lower half of the reflector 101.
[0056] In the following description, in FIG. 6, the first direction
D1 may refer to an opposite direction to gravity; the second
direction D2 may refer to a direction in which radiators (e.g.,
waveguide antennas 102a of FIG. 13) constituting the phased antenna
array 102 are arranged, and which is perpendicular to the first
direction D1; the third direction D3 may refer to a direction
perpendicular both to the first and second directions D1 and D2. In
some embodiments, the first direction D1 may refer to a direction
inclined to gravity (or to the opposite direction) depending on the
environment where the antenna device 100 is installed or on the
actual installation state. In the following description, DX, where
X is a natural number, may be used to indicate a direction or a
plane positioned in a direction.
[0057] In an embodiment, the reflector 101 and the radiating
structure may be interconnected via a supporter 103. For example,
in the third direction D3, the reflector 101 may be installed at
one end of the supporter 103 and the radiating structure (e.g., the
phased antenna array 102) may be installed at the other end of the
supporter 103. As mentioned above, the radiating structure, e.g.,
the phased antenna array(s) 102 may be arranged to illuminate at
least part of the reflector 101.
[0058] In various embodiments, the reflector 101 may have the form
of a curved plate that at least partially encloses the surroundings
of the radiating structure. For example, viewed from the radiating
structure, the first cross-section(s) of the reflector 101 cut in a
direction may have a profile of a parabolic shape, and the second
cross-section(s) of the reflector 101 cut in another direction
(e.g., a direction perpendicular to the first cross-section) may
have a profile of a hyperbolic shape.
[0059] According to various embodiments, the first cross-section(s)
may refer to the cross-section of the reflector 101 and/or the
antenna device 100 cut along a plane e.g., orthogonal to the D2-D3
plane and parallel or inclined to the D1-D3 plane. For example, a
cross-section shown in FIG. 7 is the first cross-section that is
parallel to the D1-D3 plane and obtained by cutting the reflector
101 and/or the antenna device 100 along the plane that is parallel
to the plane D1-D3 and has the line A-A' of FIG. 6 (hereinafter,
referred to as the first vertical plane). The cross-section may
refer to a cross-section of the reflector 101 and/or a cross
section of the entire antenna device 100. In the first
cross-section, the reflector 101 may have a profile of a parabolic
shape around the radiating structure (e.g., the phased antenna
array 102). In an embodiment, the edge(s) PE of the profile of the
parabolic shape of the reflector 101 (e.g., of the first
cross-section) may be formed to be directed toward the radiating
structure. For example, if a distance d from the radiating
structure to an arbitrary part of the reflector 101 is measured
along the third direction D3, the edges PE of the profile of the
parabolic shape may be at the closest positions to the radiating
structure. According to various embodiments, if the reflector 101
and/or the antenna device 100 is cut along the planes parallel or
inclined to the first vertical plane, the respective parabolic
profiles may be partially different from one another. For example,
depending on the necessary scan angle, directivity, gain, etc., for
the antenna device 100, the profile of the reflecting plane of the
reflector 101 may vary.
[0060] According to various embodiments, the second
cross-section(s) may refer to a cross-section of the reflector 101
and/or the antenna device 100 cut along a plane e.g., perpendicular
to the D1-D3 plane and parallel or inclined to the D2-D3 plane. For
example, a cross-section shown in FIG. 8 is the second
cross-section that appears from cutting the reflector 101 and/or
the antenna device 100 along a plane that is parallel to the D2-D3
plane and has the line B-B' of FIG. 6 (hereinafter, referred to as
the first horizontal plane). The cross-section may refer to a
cross-section of the reflector 101 and/or a cross section of an
entirety of the antenna device 100. In the second cross-section,
the reflector 101 may have a profile of a hyperbolic shape with
respect to the radiating structure (e.g., the phased antenna array
102). In an embodiment, the edge(s) HE of the profile of the
hyperbolic shape of the reflector 101 (e.g., of the second
cross-section) may be formed to be directed away from the radiating
structure. For example, if the distance d from the radiating
structure to an arbitrary part of the reflector 101 is measured
along the third direction D3, the edges HE of the profile of the
hyperbolic shape may be at the farthest positions from the
radiating structure. According to various embodiments, if the
reflector 101 and/or the antenna device 100 is cut along the planes
parallel or inclined to the second horizontal plane, the respective
profiles of hyperbolic shape may be partially different from one
another. For example, depending on the necessary scan angle,
directivity, gain, etc., for the antenna device 100, the profile of
the reflecting plane of the reflector 101 may be determined.
[0061] In accordance with various embodiments, the phased antenna
array 102 may include a plurality of phased antennas (e.g.,
waveguide antennas 102a of FIG. 13). For example, the plurality of
phased antennas may be linearly arranged along the second direction
D2 to form the phased antenna array 102. In an embodiment, the
aforementioned phased antennas may be arranged on the same plane as
one of the second cross-sections, e.g., a plane parallel to the
second direction D2 including a line P1 or P2 of FIG. 7. In another
embodiment, the phased antennas may be arranged in a direction
orthogonal to a symmetry axis (e.g., an axis denoted by `S` in FIG.
8) of the profile of the hyperbolic shape in the second
cross-section.
[0062] FIG. 9 is a graph representing measurements of radiation
properties of an antenna device including a cylindrical or
parabolic reflector of the related art according to an embodiment
of the present disclosure.
[0063] FIG. 10 is a graph representing measurements of radiation
properties of an antenna device including a parabolic-hyperbolic
reflector according to various embodiments of the present
disclosure.
[0064] Referring to FIGS. 9 and 10, measurements of the radiation
properties are to compare radiation properties based on the
difference in shape or profile of the reflector, and other elements
than the reflector are measured under the same conditions. The
measurement was made in the respective frequency bands of 26.65
GHz, 27.925 GHz, and 29.2 GHz.
[0065] Referring to FIG. 9, a graph resulting from measurement of
radiation patterns (e.g., directivity) of an antenna device (e.g.,
the antenna device of FIG. 2 or FIG. 3) including e.g., a reflector
with a linear cross-section according to the related art is
illustrated. As seen from FIG. 9, the antenna device of the related
art generates a main beam at a diffraction angle greater than about
+45 degrees and a parasitic diffraction lobe of a similar level to
the main beam at a diffraction angle smaller than about -45
degrees. The main beam and/or parasitic diffraction lobe has an
excessively strong transmission and reception level compared to a
gain in a main direction (direction of about 0 degree), thereby
reducing the gain in the main direction. Furthermore, the antenna
device of the related art as described above may have a scan angle
of about .+-.45 degrees, but the scan angle of the antenna device
may be narrowed as the difference between the gain in the main
direction and the gain of the main beam (and/or the parasitic
diffraction lobe) increases.
[0066] Referring to FIG. 10, a graph resulting from measurement of
radiation patterns (e.g., directivity) of an antenna device
according to various embodiments of the present disclosure is
illustrated, e.g., the antenna device 100 shown in FIG. 6. As seen
from FIG. 10, with an antenna device in accordance with various
embodiments of the present disclosure in comparison with the
antenna device of the related art, generation of parasitic
diffraction lobes is suppressed in a scan direction that exceeds
about -45 degrees, and the transmission and reception levels
(gains) in a certain range I (e.g., a range within about 30
degrees) in a scan direction that exceeds about -45 degrees remain
as similar as the gain in the main direction. As such, as the
generation of parasitic diffraction lobes is suppressed, the
antenna device in accordance with various embodiments of the
present disclosure may improve the gain in the main direction while
the scan angle may be extended to an extent of the certain range
I.
[0067] In an embodiment, compared with the gain of a range of the
scan angle of FIG. 9, the measurement result reveals that the gain
in the main direction is improved and overall gains in the range of
scan angle (about .+-.45+I) are uniform (i.e., deviations
decreases). For example, with the same other conditions, e.g., same
arrangements or performances for other elements), the antenna
device in accordance with various embodiments of the present
disclosure may improve or at least maintain the gain, efficiency,
directivity, etc., while increasing (expanding) the scan angle as
compared with the antenna device of the related art. The fact that
the profile of the hyperbolic shape (also referred to as the
hyperbolic profile) reduces the image of an object means that, for
example, applying the hyperbolic profile to the reflector
illuminated onto the phased array antenna virtually reduces an
electrical distance between radiating elements, e.g., phased
antennas, which may explain comprehensive effects of improving or
at least maintaining characteristics of the antenna device, e.g.,
gain, efficiency, directivity, etc., while increasing (expanding)
the scan angle.
[0068] The reflector with the profile of the hyperbolic shape
applied thereto may suppress generation of parasitic diffraction
lobes, and if there is no parasitic diffraction lobe, the distance
(e.g., the electric distance) between the phased antennas (e.g.,
the waveguide antennas 102a of FIG. 13) that form the phased
antenna array may meet the following Equation 1:
a = .lamda. 1 - sin ( .theta. max ) Equation 1 ##EQU00001##
[0069] In Equation 1, a indicates an electric distance between the
phased antennas, .theta..sub.max indicates the maximum beam
diffraction angle, and .lamda. indicates a wavelength.
[0070] As expressed in Equation 1, using the reflector of a
hyperbolic profile may reduce the electric distance between
radiating elements, thereby increasing the scan angle, e.g., the
maximum beam diffraction angle .theta..sub.max. In some
embodiments, as the curvature of the hyperbolic profile increases,
the larger scan angle may be provided. With the reflector of a
hyperbolic profile, the electric distance between the radiating
elements may be reduced, but an actual distance between them may
not change.
[0071] FIG. 11 shows a configuration of a base station with an
antenna device according to various embodiments of the present
disclosure.
[0072] Referring to FIG. 11, the antenna device 100 may have a scan
angle of more than about .+-.60 degrees in the D2-D3 plane. For
example, in configuring a base station, if the antenna device 100
is installed such that the line A-A' is substantially parallel to
the direction of gravity or perpendicular to the ground according
to an installation environment, beam scanning for the entire
coverage area on the D2-D3 plane, e.g., the range of 360 degrees,
is possible by combining three antenna devices 100a, 100b and 100c.
This may: [0073] improve or alleviate complexity of control and
distribution devices on the side of the base station transceiver,
[0074] reduce the number of antenna devices for beam scanning of
the entire coverage area, [0075] enable simplification and speed up
of installation of the base station as the number of antenna
devices decreases, and [0076] improve energy efficiency.
[0077] Further, the radiation pattern formation performance on
various elevation planes of the present disclosure may be improved
better than the antenna device of the related art or may at least
remain the same.
[0078] In an embodiment, the radiation structure, e.g., the phased
antenna array 102 of FIG. 6 may have a similar form to a circle or
rectangle, and may be located on the center axis of the antenna
device 100. In another embodiment, the phased antenna array 102 may
be arranged linearly and symmetrically on a horizontal plane around
the center axis of the antenna device 100. In another embodiment,
the phased antennas that form the phased antenna array 102 (e.g.,
the waveguide antennas 102a of FIG. 13) may be arranged on the same
plane as one of the aforementioned second cross-sections (e.g., a
second cross-section including the line P1 or P2 of FIG. 7 and
located on a plane parallel to the second direction D2) and
arranged in the perpendicular direction to the symmetry axis of the
profile of the hyperbolic shape formed on the plane. The shape or
arrangement of the radiating structure may be properly modified
taking into account specifications required for the antenna device
or an environment in which the antenna device is to be
installed.
[0079] Configurations on a phased antenna array (e.g., the phased
antenna array 102 of FIG. 6) of an antenna device (e.g., the
antenna device 100 of FIG. 6), a phased antenna that makes up the
phased antenna array (e.g., the waveguide antenna 102a of FIG. 13),
a feeding structure of each phased antenna, etc., will be described
with reference to FIGS. 12 to 17.
[0080] FIG. 12 is a perspective view of a phased antenna array of
an antenna device, according to various embodiments of the present
disclosure.
[0081] Referring to FIG. 12, the phased antenna array 102 may
include a waveguide member 121 and a number of waveguides 123
formed in the waveguide member 121. The waveguides 123 may be
linearly arranged in one direction (e.g., in parallel with the
second direction D2), and placed on the same plane as one of the
cross-sections of the hyperbolic profile of the reflector (e.g.,
the reflector 101 of FIG. 6). Each of the waveguides 123 has the
form that extends in a different direction (e.g., a direction
perpendicular to the second direction D2) and operates as an
antenna for transmitting or receiving electric waves by being
independently fed from one another or by being equally fed. In some
embodiments, the waveguide antenna (e.g., the waveguide antenna
102a of FIG. 13) and/or the phased antenna array 102 may perform
dual-polarized beamforming according to feeding structures applied
to the waveguides 123, internal structures of the waveguides 123,
etc. The feeding structures and internal structures of the
waveguides 123 may be suitably designed taking into account
suppression of parasitic radiation, gain, efficiency, etc., of the
antenna device. The feeding structure or internal structure of the
waveguide will be described in more detail in connection with FIG.
13.
[0082] FIG. 13 is an exploded perspective view of an implementation
of a phased antenna of an antenna device, according to various
embodiments of the present disclosure.
[0083] FIG. 14 shows an implementation of a phased antenna of an
antenna device, according to various embodiments of the present
disclosure.
[0084] FIG. 15 is a cross-sectional view of the phased antenna cut
along the line C-C' in FIG. 14, according to various embodiments of
the present disclosure.
[0085] Referring to FIGS. 13 to 15, the phased antenna array 102 as
described above in connection with FIG. 12 may be formed by
combining a plurality of waveguides 123, which may operate
independent antennas. For example, each of the waveguides 123 may
form a waveguide antenna, and the waveguides 123 may be combined to
form the phased antenna array 102. FIGS. 13 to 15 show a phased
antenna that makes up the phased antenna array 102, e.g., an
example of waveguide antenna 102a. A combination of the waveguide
antennas 102a may form the phased antenna array 102, as will be
described below.
[0086] Referring to FIGS. 13 to 15, the waveguide antenna 102a
(e.g., a radiator) may have a metal or may have a metalized hollow
structure, and include a waveguide 123 formed inside the metal or
metalized hollow. On the inner walls that form the waveguide 123,
protrusions 124a, 124b, 124c, etc., may be provided, and thus the
waveguide 123 and/or the waveguide antenna 102a may have a compound
cross-section. In an embodiment, the waveguide 123 may be a hollow
waveguide open to the reflector (e.g., the reflector 101 of FIG. 6)
on one side (e.g., a first side F1) of the waveguide antenna 102a
and closed on the opposite side (e.g., a second side F2). The
closed cross-section of the waveguide 123 may provide a reflecting
face, and the waveguide 123 may emit waves through the open
cross-section. The shape and size of the cross-section of the
waveguide 123 may meet the general principle of radio waves
propagation. For example, since the size of the cross-section of
the waveguide may determine a critical value (e.g., a critical
frequency) that cuts off penetration of radio waves, the size of
the cross-section of the waveguide 123 may be suitably designed
taking into account the critical value. The size, shape, etc., of
the cross-section of the waveguide as described above may be
adjusted by the protrusion 124a, 124b and 124c.
[0087] In various embodiments, the waveguide antenna 102a may
include at least one microstrip lines 127a and 127b for providing a
feed into the waveguide 123. In some embodiments, the microstrip
lines 127a and 127b may be formed and supported on printed circuit
boards 125a and 125b, and one end of the microstrip lines 127a and
127b extends to the inside of the waveguide 123 to form an
excitation waveguide probe inside the waveguide 123. In an
embodiment, an end (e.g., an excitation probe) of the microstrip
lines 127a and 127b may protrude into the waveguide 123 while being
perpendicular to the inner wall (or the cross-section of the
protrusion 124a, 124b and 124c) of the waveguide 123, the
protruding length being substantially about 3/4 of the height of
the waveguide. The protruding length may vary depending on
requirements for the waveguide antenna 102a. In another embodiment,
the microstrip lines 127a and 127b may be formed on either side of
the printed circuit board 125a and 125b to be symmetrically
arranged.
[0088] In various embodiments, the waveguide antenna 102a may
include a first waveguide member 121a having a first part 123a of
the waveguide 123, and a second waveguide member 121b having a
second part 123b of the waveguide 123. The microstrip lines 127a
and 127b may be placed between the first waveguide member 121a and
the second waveguide member 121b. The printed circuit boards 125a
and 125b having the microstrip lines 127a and 127b may be placed on
a plane perpendicular to a direction in which the waveguide 123
extends or to an axis parallel with the direction. For example, the
printed circuit boards 125a and 125b may be placed between the
first part 123 and the second part 123b, and thus clamped between
the first and second waveguide members 121a and 121b. In some
embodiments, the printed circuit board 125a and 125b (if there are
many, one printed circuit board) may be placed at an about 1/4
wavelength distance from the closed end of the waveguide 123,
dividing the waveguide 123 into the first part 123a and the second
part 123b.
[0089] In an embodiment, the first waveguide member 121a may be
produced with e.g., a metal, and the first part 123a may be opened
on a side directed toward the second waveguide member 121b and/or
the reflector (e.g., the reflector 101 of FIG. 6) and closed on the
opposite side, e.g., on the second side F2 of the waveguide antenna
102a. In another embodiment, the second waveguide member 121b may
be produced with, e.g., a metal, and the second part 123b may be
opened on both sides, e.g., the side directed toward the first
waveguide member 121a and the side (e.g., the first side F1 of the
waveguide antenna) directed toward the reflector (e.g., the
reflector 101 of FIG. 6). For example, the waveguide 123 may be
comprised of a combination of the first part 123a and the second
part 123b.
[0090] According to various embodiments, the protrusion(s) 124a,
124b and 124c are for control of critical frequency, penetration of
vertical and/or horizontal polarization, etc., and may have various
shapes, sizes, positions, etc. For example, the protrusion(s) 124a,
124b and 124c may make the critical frequency of the waveguide
antenna 102a low by adjusting e.g., the size of the cross-section
of the waveguide 123. In an embodiment, the protrusion(s) 124a,
124b and 124c may be formed between the closed end of the waveguide
123 and one of the printed circuit boards (e.g., the printed
circuit board denoted by 125a), between the other printed circuit
board (e.g., the printed circuit board denoted by 125b) and the
open end of the waveguide 123, and even in an opening 123c of a
dummy waveguide member 121c, which will be described later, if
there are a plurality of printed circuit boards 125a and 125b, and
may have various shapes based on specifications required for the
waveguide antenna 102a.
[0091] In various embodiments, the waveguide antenna 102a may
further include furrows 129a and 129b formed in the first and
second waveguide members 121a and 121b, respectively. If the
printed circuit boards 125a and 125b are fixed between the first
and second waveguide members 121a and 121b, the furrows 129a and
129b may be positioned to correspond to the areas in which
microstrip lines 127a and 127b are formed. For example, the furrows
129a and 129b may prevent the microstrip lines 127a and 127b from
coming into contact with the metal part of the first and/or second
waveguide members 121a and 121b, and create an environment for
propagation of TEM waves. The line width of the microstrip lines
127a and 127b, the width of each of the furrows 129a, 129b, etc.,
may be designed differently depending on e.g., impedance required
for the waveguide antenna 102a.
[0092] In an embodiment, the printed circuit board 125a and 125b
may be provided in the plural, and each printed circuit board may
provide a different feeding structure. For example, the waveguide
antenna 102a may perform dual-polarized beamforming by being fed
through different feeding structures. More specifically, in a case
that there are two printed circuit boards 125a and 125b provided, a
microstrip line placed on the first one of the printed circuit
boards 125a and 125b may be arranged in the direction perpendicular
to a microstrip line placed on the second printed circuit board,
and the waveguide 123 may create orthogonal dual polarizations
(e.g., horizontal and vertical polarizations) by being fed from the
respective microstrip lines 127a and 127b).
[0093] In some embodiments, if the waveguide antenna 102a includes
a plurality of printed circuit boards 125a and 125b, there may be
the dummy waveguide member 121c placed between the printed circuit
boards 125a and 125b. In some embodiments, the dummy waveguide
member 121c may have the same metal or metalized hollow structure
as that of the first and/or second waveguide member 121a and 121b.
For example, as the dummy waveguide member 121c is produced with a
metal, it may include an opening 123c that corresponds to the first
and/or second part 123a and 123b of the waveguide 123. In another
embodiment, if the microstrip lines 127a and 127b are placed on
either side of each of the printed circuit boards 125a and 125b,
the dummy waveguide member 121c may also include furrows 129c that
correspond to the areas in which the microstrip lines 127a and 127b
are formed.
[0094] In various embodiments, the waveguide antenna 102a may
include feeding terminals 227a and 227b formed on some of its
sides. The feeding terminals 227a and 227b may partially include at
least a combination of the microstrip lines 127a and 127b and the
furrows 129a and 129b, and may each be connected to a wireless
communication module (RFIC). In an embodiment, the first of the
feeding terminals (e.g., the feeding terminal denoted by 227a) may
be fed for creating vertical polarization, and the second feeding
terminal (e.g., the feeding terminal denoted by 227b) may be fed
for creating horizontal polarization. The wireless communication
module RFIC may provide independent or identical feeding signals to
the feeding terminals 227a and 227b.
[0095] The structure of the waveguide antenna 102a may be
diversified depending on embodiments. For example, a single printed
circuit board may be provided and microstrip lines may be provided
on either side of the single printed circuit board. In an
embodiment, on one side of the single printed circuit board, a
plurality of microstrip lines may be arranged to cross one another
at right angles to provide feed for dual polarization. In another
embodiment, if the waveguide antenna 102a is an antenna that
generates single polarization, the structure of arranging the
printed circuit board, the microstrip lines, etc., may become a bit
simpler. In yet another embodiment, if the waveguide antenna 102a
is an antenna that generates single polarization, neighboring
waveguide antennas may radiate differently polarized waves.
[0096] FIGS. 16 and 17 show feeding structures of an antenna
device, according to various embodiments of the present
disclosure.
[0097] Referring to FIGS. 16 and 17, the phased antenna array
(e.g., the phased antenna array 102 of FIG. 12) and/or the
waveguide antenna (e.g., the waveguide antenna 102a of FIG. 13) may
include a fixed printed circuit board between the first waveguide
member 121a and the dummy waveguide member 121c, and a feeding
structure may be formed by combining the microstrip lines 127a and
the furrows 129a and 129c. In some embodiments, with a single
printed circuit board arranged, the printed circuit board may be
fixed between the first and second waveguide members 121a and 121b.
The microstrip lines 127a, as mentioned above, may be symmetrically
arranged on either side of the printed circuit board 125a. The
microstrip lines 127a may be placed in the space defined by the
furrows 129a and 129c and some region of the printed circuit board
125a (e.g., an area in which the microstrip lines 127a are
formed).
[0098] In various embodiments, if a feeding signal is applied to
the aforementioned feeding structure, e.g., the feeding structure
in which the microstrip lines 127a are placed in some space,
distribution of the electromagnetic fields may be optimized to be
concentrated in the air around the microstrip lines 127a (e.g., in
the space in which the microstrip lines 127a are placed). This may
substantially reduce the loss in the feeding structure and improve
antenna efficiency. For example, the loss of a typical microstrip
line with H=0.8 mm and frequency of 28 GHz using Taconic TLY-based
dielectric is about 0.5 dB/cm, whereas in the feeding structure in
accordance with various embodiments of the present disclosure, it
may be seen that the loss of the microstrip lines 127a and 127b is
merely about 0.1 dB/cm with an air filling structure in which the
first and second waveguide members 121a and 121b (and/or the dummy
waveguide member 121c) are used as ground and some space is formed
around the microstrip lines 127a and 127b.
[0099] By arranging such feeding structures to be perpendicular to
each other, dual-polarized beamforming is enabled, in which case
cross-polarization may be suppressed to within about -15 dB and the
antenna device (e.g., the antenna device 100 of FIG. 6) may
maintain high efficiency. With the configuration, the antenna
device in accordance with various embodiments of the present
disclosure may form the required amplitude-phase distribution or
shape of the radiation pattern in the elevation plane or horizontal
plane to conform to particular conditions required depending on the
installation environment.
[0100] Although somewhat different depending on the actual size,
shape, etc., the antenna device (e.g., the antenna device 100 of
FIG. 6) with a combination of the phased antenna array consisting
of the waveguide antennas and a parabolic-hyperbolic profile may
have a scan angle of about 60 degrees, enable dual-polarized
beamforming with the feeding structures (e.g., the feeding
structure of FIG. 16) of the waveguide antenna (e.g., the waveguide
antenna 102a of FIG. 13), attain almost 74% of energy efficiency,
and suppress the feeding loss to less than about 1.5 dB. The
antenna device may conform to e.g., the next generation
communication standard (e.g., fifth generation (5G) standard), and
may be usefully used in mobile millimeter-wave networks, such as
automobile radar, search radar, etc.
[0101] FIG. 18 shows a vertical (elevation) plane radiation pattern
of an antenna device including a cylindrical or parabolic reflector
of the related art according to an embodiment of the present
disclosure.
[0102] FIG. 19 shows a vertical plane radiation pattern of an
antenna device, according to various embodiments of the present
disclosure.
[0103] Referring to FIG. 18, since the antenna device of the
related art is unable to secure a sufficient scan angle on a
vertical plane, additional beam scanning may be required. The
additional beam scanning may increase complexity of e.g., a
controller, a distributor, and the like on the transceiver side. An
additional antenna device needs to be installed to provide
sufficient waves across the entire coverage area without the
additional beam scanning.
[0104] Referring to FIG. 19, by applying in the elevation plane the
cosecant pattern easily implemented by the antenna device (e.g.,
the antenna device 100 of FIG. 6), even without installation of
additional beam scanning or additional antenna device, sufficient
waves may be provided across a desired coverage area (at least the
coverage area shown in FIG. 18), and a stable wireless
communication environment may be provided without a loss of gain
even at the edges of the coverage area.
[0105] In various embodiments, the antenna device may operate in
multiple inputs multiple outputs (MIMO) mode.
[0106] FIG. 20 shows calculation of a profile of a hyperbolic shape
of a reflector in an antenna device according to various
embodiments of the present disclosure.
[0107] Referring to FIG. 20, in various embodiments of the present
disclosure, the hyperbolic profile of a reflector (e.g., the
reflector 102 of FIG. 6) may be calculated by the following
Equation 2. In Equation 2, M is an initial parameter, which may be
chosen from among a range of 1.3 to 1.6. If the initial parameter
has a larger value out of the range, the scan angle may increase
but the antenna gain may be reduced as illustrated in Equation 2
below:
x=a.times.Cos h(t)
y=b.times.Sin h(t) Equation 2
where
a = f .times. ( M - 1 ) 2 M , b = f .times. ( f - 2 a ) ,
##EQU00002##
t denotes a free parameter, and f denotes a focal distance (see
FIG. 20).
[0108] In accordance with various embodiments of the present
disclosure, an antenna device may include a reflector having a
profile of a parabolic shape in a first cross-section cut parallel
to a first direction and a profile of a hyperbolic shape in a
second cross-section, the second cross-section being cut
perpendicular to the first direction and crossing the first
cross-section at right angle; and a radiating structure having at
least one phased antenna array adapted to illuminate at least part
of the reflector and to scan a beam, wherein edges of the profile
of the parabolic shape of the first cross-section are formed to be
directed toward the radiating structure, and edges of the profile
of the hyperbolic shape of the reflector are formed to be directed
away from the radiating structure.
[0109] In various embodiments, the phased antenna array may include
linearly-arranged phased antennas.
[0110] The phased antennas are placed on the same plane as one of
the second cross-sections, and arranged to be orthogonal to the
symmetry axis of the profile of the hyperbolic shape.
[0111] In various embodiments, the radiating structure may include
at least two phased antenna arrays, which may be arranged to
illuminate different parts of the reflector.
[0112] In various embodiments, the phased antenna array may perform
dual-polarized beamforming.
[0113] In various embodiments, the phased antennas constituting the
phased antenna array may include waveguide antennas.
[0114] In various embodiments, the waveguide antenna may include a
waveguide with a side directed toward the reflector open and the
opposite side closed.
[0115] The waveguide may be formed inside a metal or metalized
hollow.
[0116] In various embodiments, the waveguide antenna may include a
waveguide having a metal or metalized hollow; and a microstrip line
providing feed into the waveguide.
[0117] In various embodiments, the waveguide antenna may include a
first waveguide member having a first part of the waveguide; a
second waveguide member having a second part of the waveguide; and
at least one printed circuit board having the microstrip line,
wherein the printed circuit board is arranged on a plane
perpendicular to an axis of the waveguide between the first and
second parts to be clamped between the first and second waveguide
members.
[0118] In various embodiments, the waveguide antenna may further
comprise furrows formed in the first and second waveguide members,
and the furrows may be formed to correspond to areas in which the
microstrip lines are formed.
[0119] In various embodiments, the microstrip line may linearly
extend on the printed circuit board, and one end of the microstrip
line extends into the waveguide and is arranged to form a right
angle with an inner wall of the waveguide, thereby forming an
excitation waveguide probe in the waveguide.
[0120] In various embodiments, the microstrip lines may be
symmetrically arranged on either side of the printed circuit
board.
[0121] In various embodiments, the waveguide antenna may include
two of the printed circuit boards, and the microstrip line placed
on one of the printed circuit boards may be arranged to be
perpendicular to the other microstrip line placed on the other
printed circuit board.
[0122] In various embodiments, the waveguide antenna may include a
dummy waveguide member arranged between two of the printed circuit
boards.
[0123] In various embodiments, the dummy waveguide may include an
opening corresponding to the first part or the second part.
[0124] In various embodiments, the waveguide antenna may further
include protrusions formed along the inner wall of the waveguide,
and the protrusions may lower the critical frequency of the
waveguide antenna.
[0125] While the present disclosure has been shown and described
with reference to various embodiments thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the present disclosure as defined by the appended
claims and their equivalents.
* * * * *